1. Field of the Invention
This invention relates to a flow through type glass electrode.
2. Description of the Prior Art
There has been proposed, as disclosed in U.S. patent application Ser. No. 614,225, filed May 24, 1984, and now U.S. Pat. No. 4,519,890, a flow-through type glass electrode which is small-sized, has superior shock resistance, can measure a minute sample, and is easy to assemble as compared with a conventional flow through type glass electrode.
This flow through type glass electrode, as shown in FIG. 4, has support tubes 23 heat-sealed to the ends of the response glass tube 22, and a sleeve 24 is heat-sealed to the support tubes 23. An internal electrode 25 and internal liquid 26 are sealed into the sleeve 24, thereby forming the main body D of the flow through type glass electrode. The main body D is contained in a resin block 27. Sample gas flows through tubes 28 equal in diameter to the response glass tube 22 and which extend through the block walls 29 respectively, the flow through tubes 28 and support tubes 23 being joined by couplers 30. Insulating material fills the main body D.
Such construction, has dead spaces 32 at the heat-sealed portions between tubes 22 and 23, and the dead space 32 and tube joint portions 33 between tubes 23 and 28 are liable to stain, which can cause clogging in the fluid passage.
Further, because of the heat-sealing, the glass of the response glass tube 22 and support tube 23 should have the same thermal expansion coefficient. Nevertheless, the flow through tube is weak in resistance to thermal shock because of low strength at the heat-sealed portions.
There is thus room for improvement in the glass electrode structure.